function User(name, age) {
  this.name = name;
  this.age = age;
}
User.prototype.show = function() {
  console.log(this.name, this.age);
};

function entend(sub, sup) {
  sub.prototype = Object.create(sup.prototype);
  Object.defineProperty(sub.prototype, "constructor", {
    value: sub,
    enumerable: false
  });
}

function Admin(...args) {
  User.apply(this, args);
}
entend(Admin, User);

function Member(...args) {
  User.apply(this, args);
}
entend(Member, User);
let xj = new Admin("向边", 18);
xj.show();
let lisi = new Member("李四", 19);
lisi.show();
